<template>
  <div class="star" :class="starType">
    <span v-for="itemClass in itemClasses" :class="itemClass" class="star-item" track-by="$index"></span>
  </div>
</template>

<script type="text/ecmascript-6">
  // 星星的总长度
  const LENGTH = 5;
  const CLS_ON = 'on';
  const CLS_HALF = 'half';
  const CLS_OFF = 'off';
  export default {
    props: {
      size: {
        type: Number
      },
      score: {
        type: Number
      }
    },
    computed: {
      // starType样式（定义显示图片的大小）
      starType () {
        return 'star-' + this.size;
      },
      itemClasses() {
        let result = [];
        // 向下取整减半，可以获得半星
        let score = Math.floor(this.score * 2) / 2;
        // 有没有小数( 不为0则表示有小数位)
        let hasDecimal = score % 1 !== 0;
        // 全星个数
        let integer = Math.floor(this.score);
        for (let i = 0; i < integer; i++) {
          result.push(CLS_ON);
        }
        // 如果有半星则追加至数组中
        if (hasDecimal) {
          result.push(CLS_HALF);
        }
        // 最后添加暗星
        while (result.length < LENGTH) {
          result.push(CLS_OFF);
        }
        return result;
      }
    }
  };
</script>

<style lang="stylus" rel="stylesheet/stylus">
  @import "../../common/stylus/mixin"

  .star
    .star-item
      display: inline-block
      background-repeat: no-repeat

    &.star-48
      .star-item
        width: 20px
        height: 20px
        margin-right: 22px
        background-size: 20px 20px
        &:last-child
          margin-right: 0px
        /* itemClass的值 */
        &.on
          bg-image('./image/star48-on')
        &.half
          bg-image('./image/star48-half')
        &.off
          bg-image('./image/star48-off')
    &.star-36
      .star-item
        width: 15px
        height: 15px
        margin-right: 16px
        background-size: 15px 15px
        &:last-child
          margin-right: 0px
        &.on
          bg-image('./image/star36-on')
        &.half
          bg-image('./image/star36-half')
        &.off
          bg-image('./image/star36-off')
    &.star-24
      .star-item
        width: 10px
        height: 10px
        margin-right: 3px
        background-size: 10px 10px
        &:last-child
          margin-right: 0px
        &.on
          bg-image('./image/star24-on')
        &.half
          bg-image('./image/star24-half')
        &.off
          bg-image('./image/star24-off')
</style>
